The present invention relates to a moving vehicle. More particularly, the invention relates to a moving vehicle equipped with a track device.
Referring to FIG. 6, a moving vehicle 50 of the prior art has the ability to travel on a jagged and extremely uneven road surface. Moving vehicle 50 has a vehicle body 51 with a plurality of track drive device 100 which function in place of wheels on an ordinary vehicle. A drive to provide motive force to the track drive devices is provided but not shown in the drawing. The drive means has a drive shaft for each track drive mechanism 100. A drive source provides the drive shaft with torque. Each track drive mechanism 100 is placed at the end of drive shaft 52.
Referring to FIG. 7, in the track drive mechanism 100 of the prior art, an input axis 101 transfers torque from drive shaft 52 of the drive means to a rotating wheel 103A. A power transfer means 105 transfers the rotation of input axis 101 to rotating wheel 103A. A support member 102 supports input axis 101, which rotates freely at the center by way of a bearing. Three rotating wheels 103A, 103B, and 103B are located at equal distances from the center of input axis 101 about which they can rotate. An endless, track 104 wraps around rotating wheels 103A, B, and C.
Rotating wheels 103A, 103B, 103B are positioned at equal distances from the center by support member 102. Referring to FIG. 7(A), track 104 is wrapped in an approximate equilateral triangle around rotating wheels 103A, 103B, 103B. Rotating wheel 103A is a chain sprocket wheel used to drive the track. The torque transmitted to rotating wheel 103A is transmitted to other wheels 103B and 103C via track 104.
Power transfer means 105 is equipped with a main driving sprocket wheel 105A which is anchored to input axis 101. A coupled driving sprocket wheel 105B, has the same axis as, and is linked to, rotating wheel 103A. An endless circular belt 105C links sprocket wheels 105A and 105B.
Moving vehicle 50 uses track drive mechanism 100 of the prior art as a wheel. Under normal conditions, torque is transferred from input axis 101 to rotating wheel 103A by way of power transfer means 105. Rotating wheels 103A, 103B, 103B forms an approximate equilateral triangle, and track 104 drives along the boundary edge of the triangle. Travel occurs without the rotation of support member 102.
If travel by track 104 is hindered by a Jagged or partly blocked or uneven road surface, wheel 103A is halted. Torque transmitted to input axis 101 drives the entire support member 102 to rotate about axis 101. That is, all of track drive mechanism 100 rotates as a single wheel. Bumps of a size that can be tolerated by the equilateral triangle track mechanism defined by three the rotating wheels 103A, 103B, and 103B can be traveled over.
In this example of the prior art, input axis 101 of track drive mechanism 100 is connected to the same axis as drive shaft 52 which projects from the side of vehicle body 51. As a result, vehicle body 51 can only be maintained at approximately the same height as the distance between input axis 101 of track drive mechanism 100 and the road surface.
There is a height H between the base of vehicle body 51 and the road surface. Referring to FIG. 8, if track drive mechanism 100 is an approximate equilateral triangle with a side of length L, then H=(L/2).tan(30.degree.). Height H is approximately 0.2887 times L. Compared to the overall size of track drive mechanism 100, vehicle body 51 does not have great clearance height. As a result, referring to FIG. 9, collisions between obstacles and vehicle body 51 may occur easily between the pair of track drive mechanisms 100 acting as front wheels. In this situation, travel is either impossible or causes damage to vehicle body 51.
Referring to FIG. 7(B), in track drive mechanism 100 of the prior art, power transfer means 105 juts out of the area protected by track 104. Referring to FIG. 10, this results in collisions with obstacles becoming more likely, particularly when coupled driving sprocket 105B moves lower as support member 102 rotates. Concerns about damage and breakdown will result.